Why will they descend from their thrones and remove their royal garments?
Radak: They will fear for themselves. They will say, a great commerce city like this was destroyed ? how will we stand?!
What is the significance of "Charados Yilbashu"?
Malbim: After removing their robes, they will be dressed in fear. I.e. they will wear sackcloth and ashes, which show their fear.
What is the significance of sitting on the ground?
Malbim: This corresponds to descending from their thrones.
What is the meaning of "v'Chardu li'Rga'im"?
Rashi, Targum Yonasan: They will be terrified due to the breakage, lest it come upon them. Rega'im is an expression of breakage, like "Roga ha'Yam" (Yeshayah 51:15), "Ori Raga" (Iyov 7:5).
Rashi citing Menachem: Rega'im is an expression of Rega (a moment), like "Ki Rega b'Apo" (Tehilim 30:6). Radak ? i.e. they will fear constantly. Malbim - they will fear every moment, lest the enemy come upon them.
What is "Shamemu"?
Rashi: It is an expression of Timhon (astonishment).
Malbim: They will mourn over your affliction.
